Authorities in western Germany have pulled the plug on one of the country's most popular open-air rock festivals because of a storm warning.

Organisers of Rock am Ring said on Sunday that they accepted the decision "out of responsibility for the welfare" of the 90,000 festival-goers.

Scores of people were injured at the site near Mendig, 100 kilometres (62 miles) west of Frankfurt, when lightning and heavy rain struck the festival late on Friday. The German Red Cross said 72 people were taken to hospital.

The festival was suspended after the incident but briefly reopened Saturday night, before the final decision to close it on Sunday.

Germany, France and Belgium have been hit by severe storms that caused heavy flooding and at least 16 deaths in recent days.

People walk through the mud after a thunderstorm hit the open air music festival ' Rock am Ring' in Mendig, Germany (Thomas Frey/dpa via AP)